From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id F0A116B0005 for ; Thu, 7 Jun 2018 14:39:27 -0400 (EDT) Received: by mail-pg0-f69.google.com with SMTP id e11-v6so3828668pgt.19 for ; Thu, 07 Jun 2018 11:39:27 -0700 (PDT) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id t14-v6si3582316pgr.275.2018.06.07.11.39.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Jun 2018 11:39:27 -0700 (PDT) Received: from mail-wm0-f54.google.com (mail-wm0-f54.google.com [74.125.82.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 68B8A208AC for ; Thu, 7 Jun 2018 18:39:26 +0000 (UTC) Received: by mail-wm0-f54.google.com with SMTP id r125-v6so20997952wmg.2 for ; Thu, 07 Jun 2018 11:39:26 -0700 (PDT) MIME-Version: 1.0 References: <20180607143855.3681-1-yu-cheng.yu@intel.com> <20180607143855.3681-4-yu-cheng.yu@intel.com> In-Reply-To: <20180607143855.3681-4-yu-cheng.yu@intel.com> From: Andy Lutomirski Date: Thu, 7 Jun 2018 11:39:12 -0700 Message-ID: Subject: Re: [PATCH 3/7] mm/mmap: Add IBT bitmap size to address space limit check Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Yu-cheng Yu Cc: LKML , linux-doc@vger.kernel.org, Linux-MM , linux-arch , X86 ML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , "H. J. Lu" , "Shanbhogue, Vedvyas" , "Ravi V. Shankar" , Dave Hansen , Jonathan Corbet , Oleg Nesterov , Arnd Bergmann , mike.kravetz@oracle.com On Thu, Jun 7, 2018 at 7:42 AM Yu-cheng Yu wrote: > > The indirect branch tracking legacy bitmap takes a large address > space. This causes may_expand_vm() failure on the address limit > check. For a IBT-enabled task, add the bitmap size to the > address limit. > > Signed-off-by: Yu-cheng Yu > --- > arch/x86/include/uapi/asm/resource.h | 5 +++++ > include/uapi/asm-generic/resource.h | 3 +++ > mm/mmap.c | 8 +++++++- > 3 files changed, 15 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/uapi/asm/resource.h b/arch/x86/include/uapi/asm/resource.h > index 04bc4db8921b..0741b2a6101a 100644 > --- a/arch/x86/include/uapi/asm/resource.h > +++ b/arch/x86/include/uapi/asm/resource.h > @@ -1 +1,6 @@ > +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */ > +#ifdef CONFIG_X86_INTEL_CET > +#define rlimit_as_extra() current->thread.cet.ibt_bitmap_size > +#endif > + > #include > diff --git a/include/uapi/asm-generic/resource.h b/include/uapi/asm-generic/resource.h > index f12db7a0da64..8a7608a09700 100644 > --- a/include/uapi/asm-generic/resource.h > +++ b/include/uapi/asm-generic/resource.h > @@ -58,5 +58,8 @@ > # define RLIM_INFINITY (~0UL) > #endif > > +#ifndef rlimit_as_extra > +#define rlimit_as_extra() 0 > +#endif > > #endif /* _UAPI_ASM_GENERIC_RESOURCE_H */ > diff --git a/mm/mmap.c b/mm/mmap.c > index e7d1fcb7ec58..5c07f052bed7 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -3255,7 +3255,13 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, > */ > bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) > { > - if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) > + unsigned long as_limit = rlimit(RLIMIT_AS); > + unsigned long as_limit_plus = as_limit + rlimit_as_extra(); > + > + if (as_limit_plus > as_limit) > + as_limit = as_limit_plus; > + What happens if as_limit_plus overflows? I guess it's probably okay here.